An investigation into small streams of contaminated air containing irritant gases and/or aerosols will be continued. Side-stream cigarette smoke, with aldehyde concentrations some 10 to the 4th power times the diluted concentrations usually reported is to be used as a model contaminant for various occupational contaminant streams. Momentary peak concentrations at nearby locations will be examined using smoke aerosol as a tracer. Usual air sampling techniques using breathing zone and personal sampling have been demonstrated to be irrelevant to potential eye irritation, and more meaningful descriptions of contaminantion will be sought. Control methods for hot contaminant streams will also be investigated. In particular, the possibility of capture near the source, with particular filtration and recirculation of filtered, diluted air contaminant will be investigated as a means of reducing irritant concentrations. The filtration and recirculation method appears to have possibilities in that a major portion of the formaldehyde and acrolein content of cigarette smoke is associated with the particulate phase.